ABSTRACT
SPECULATIONS ABOUT THE ENGINES THAT DRIVE HUMAN BEHAVIOR ARE as old as recorded human history. Certainly every enduring work of drama or fiction, from the Oresteia cycle of ancient Greece onward, can be interpreted as an account of the antecedents and/or consequences of a particular set of human behaviors on the part of particular persons, and it is likely that these works have endured precisely because the accounts they offer seem to hold some general applicability. There followed many centuries of more-and-less sophisticated speculation on the part of litterateurs, philosophers, theologians, and physicians.
